1. Field of the Invention
The present invention relates to the automobile rear structure.
2. Description of the Related Art
Conventionally, there has been proposed the under-floor structure of a rear portion of an automobile having the following constitution (see Japanese Patent Application Laid-Open 7-165126, for example). That is, a rear overhang portion is positioned above an under-floor surface of a wheel base portion, and a muffler having an approximately flattened cross-sectional shape is arranged in a horizontally installed state below the under-floor surface in the vicinity of the rear overhang portion. Further, a lowermost surface of the muffler is positioned above the under-floor surface of the wheel base portion and below a lower end of a rear bumper. This under-floor structure can prevent the lowering of a flow speed of air which flows below a floor of a vehicle body and the peeling-off of such air by making the muffler function as an aerodynamic part thus enhancing the aerodynamic performance of the automobile.
Here, there may exist a case that a portion of exhaust gas discharged from the muffler enters a space defined between a rear bumper cover and the vehicle body, and such exhaust gas which enters the space defined between the rear bumper cover and the vehicle body and a pressure thereof are discharged downwardly from a space defined between the rear bumper cover and the vehicle body, and is vertically merged with an air flow below the floor of the vehicle body. In this case, the air flow below the floor of the vehicle body is disturbed thus becoming a cause to deteriorate the aerodynamic performance of the automobile.